In a mobile radio communication system such as WCDMA (Wideband Code Division Multiple Access), LTE (Long Term Evolution), LTE-A (LTE-Advanced) and WiMAX (Worldwide Interoperability for Microwave Access) by 3GPP (Third Generation Partnership Project), the communication area can be increased by establishing a cellular configuration in which the area covered by a base station device (base station, transmission station, downlink transmission device, uplink reception device, eNodeB) or a transmission station conforming to the base station device is arranged as a plurality of cells. Furthermore, by using a frequency differing between adjacent cells or sectors, even a terminal device (mobile station, receiving station, uplink transmission device, downlink reception device, mobile terminal, UE: User Equipment) located in a cell edge region or a sector edge region can carry out communication without suffering interference by a transmitted signal from a plurality of base stations. However, such a scheme had the problem that the frequency usage efficiency is low. Although the frequency usage efficiency can be improved by using the same frequency between adjacent cells or sectors, measures against interference for the terminal device located in the cell edge region will be required.
By adaptively controlling a modulation and coding scheme (MCS), the number of spatial multiplex (number of layers, rank), precoder and the like according to the state of a transmission path between a base station and a terminal device, more efficient data transmission can be realized. Non-Patent Literature 1 discloses a method of performing such control.
FIG. 26 represents a base station 2601 and a terminal device 2602 adaptively controlling a precoder in LTE. When a precoder is adaptively controlled with respect to a downlink transmission signal 2603 that is transmitted in LTE, terminal device 2602 refers to a downlink reference signal (RS) included in downlink transmission signal 2603 that is transmitted from base station 2601 to calculate a rank indicator RI specifying a preferred number of spatial multiplex, a precoding matrix information PMI (Precoding Matrix Indicator) specifying a preferred precoder, and a channel quality indicator CQI specifying a preferred transmission rate, and reports to base station 2601 via an uplink channel 2604. Non-Patent Literature 1 teaches a feedback mode in which precoder information is reported periodically. A terminal device that is configured with a feedback mode in which the precoder information is reported uses a code book that is a table including a plurality of predetermined precoding matrixes to calculate and report to the base station a PMI that is an index corresponding to a preferred precoding matrix in the relevant code book.